Most gamblers don’t go broke because their strategy is bad. They go broke because they don’t know how to size their bets. This Bankroll Unit Calculator divides your capital into optimal, variance-adjusted units to protect you from cold streaks (check our deep dive into the mathematics of Risk of Ruin to see this in action).
A betting unit is the standard size of a single wager, expressed as a percentage of your total bankroll. Professional gamblers never think in dollar amounts; they think in units (check our deep dive into the mathematics of Risk of Ruin to see this in action).
If you tell a professional sports bettor that you won $1,000 last night, they won’t know if that is impressive or reckless. If you tell them you won **5 units**, they immediately understand your success relative to your risk. Sizing your bets in units ensures that as your bankroll grows, your stakes scale up safely—and when your bankroll shrinks, your wagers automatically scale down to prevent bankruptcy.
This calculator helps you determine your optimal unit size based on three standard risk profiles:
Ideal for players who want to minimize the probability of ruin to near zero. A conservative unit size is typically **0.5% to 1.0%** of your total bankroll. This profile is essential for high-frequency betting (like sports betting or high-speed blackjack) where you place hundreds of wagers per week and are exposed to long-term variance.
The standard benchmark for most disciplined players. A balanced unit size is exactly **1.0%** of your bankroll. This provides a clean compromise between capital growth speed and protection against standard downswings. It allows you to survive a 10-bet losing streak with 90% of your bankroll still intact.
Only suitable for low-variance strategies or recreational sessions where you are comfortable with a high probability of going broke. An aggressive unit represents **2.0% to 3.0%** of your bankroll. If you experience a brief sequence of cold cards or missed sports hedges, your bankroll will enter a death spiral before you can recover.
Let’s look at the real-world impact of unit sizing. Imagine two sports bettors, Player A and Player B. Both start with a bankroll of $5,000.
Both bettors experience a standard cold run: they lose 6 consecutive wagers.
For **Player A**, losing 6 bets cost them $300. Their bankroll drops to $4,700. They have lost just 6% of their capital, and they still have 94 units left to play. They don’t need to panic, and they can comfortably wait for the variance to balance out.
For **Player B**, that same 6-bet cold streak costs them $1,500. Their bankroll crashes to $3,500—a massive 30% wipeout of their entire capital. Desperation kicks in, prompting them to chase losses with larger bets, leading directly to bankruptcy.
Ideally, you should adjust your unit size dynamically. If your bankroll grows or shrinks by 10% to 20%, recalculate the dollar value of your unit. This locks in your profits during winning runs and cushions your falls during downswings.
Absolutely. If you play high-variance games like slots or place sports parlay bets, you need more units (typically 300+ units) to survive the dry spells. For low-variance games like blackjack or single-zero roulette, 100 units is generally safe.
Static betting keeps your unit size exactly the same regardless of your balance. Proportional betting recalculates your unit size after every single wager. Proportional betting makes it mathematically impossible to go broke (since your bet size shrinks toward zero), but it can be tedious to calculate manually.